Fibrous product



Patent ed Jan. 21, 1941 2,229,357 I UNITED STATES J PATENT OFFICE rmnonsrnonuc'r Gordon E. Wightman, Upper Montclaiig'N. .I., and

Ernest Kritzmacher, Manchester, Conn., assignors, by mesne assignments,to Union Carbide and Carbon Corporation, New York, N. Y., acorporationof New York No Drawing. Application January 25, 1937,

- Serial No. 122,312

3 Claims. (CI. 92-40) This invention relates to the production of sionof about 30% resin content. Generally paper or other fibrous sheetmaterial having a speaking, resinous compositions of the characterresinous substance associated therewith for the above described arespoken of as being hydro-philic purpose of increasing the resistance ofthe mateor water loving in nature, but for the purposes 5 rial tomoisture, and is particularly directed to a of this invention, onlythose resinous composi- 5 new method of producing such material and totions which will tolerate the addition of substan-' the novel productsthereby produced. tially more than an equal amount of water with- One ofthe purposes of the invention is to proout becoming turbid or cloudywill be designated vide a method of eiiectively associating a resinashydrophile. It will be seen therefore that the ous substance with thefibers of paper or like hydrophile compositions utilized in the presentmaterialinvention are characterized by containing a It is known to treatpaper and like material resinous product capable of holding up toseventy with rosin to impart water resistance thereto. parts of waterper thirty parts of the resinous The usual practice is to add to the wetfibrous product, even in neutral condition.

' pulp a rosin soap made by boiling rosin with A further distinguishingfeature of these .sodium carbonate. After mixing the rosin soapfilterable hydrophile resinous compositions is the with the pulp therosin is precipitated by the relatively small amount of resinoidmigration addition of alum and the pulp is then formed into which occursin fibrous sheets treated with these a sheet or board and dried.compositions. Thus, when the volatile portion of It has also beenproposed to dissolve rosin in a the hydrophile resinous composition isremoved, '2 solvent immiscible with water, such as carbon as for exampleby evaporation,-the resinoid aptetrachloride, and apply the solution tothe prepears to remain in the form of adhesive films forme g sheet,after which the solvent is removed upon individual parts of or withinthe fibers therefrom. themselves, instead of migrating to the exposedThe first method entails the disadvantage that surfaces of the fibers,as is so often the case 25 the addition of alum to efiect precipitationof when organic solvent dispersions of comparable the rosin results inthe presence of iree acid resinoid concentration are used. which injuresthe fibers. The second method re- Of particular value in the presentinvention are quires the drying of the sheet before it can be beathardenable resinous substances or res- '30 treated with the rosinsolution, and a subsequent inoids, especially those substances whichchange drying operation is required for removing the to a hydrophobecondition upon the application solvents from the sheet. Apparatus forrecoverof heat so that, in the final heat treated condiing the solventis also required. A further distion, they are substantially unaffectedby moisadvantage of this method'is that the solvents ture. Especiallysuitable substances for use in tend to carry the solute to the surfaceof the sheet the present invention are the liquid masses 010- 05 andconcentrate it there upon evaporation. tainable by reacting aboutequimolecular propor-' These d sadvantages are eliminated by the tionsof phenol or cresol with aqueous formaldepresent invention whichcomprises the treathyde in the presence of a small amount, say 1 ment ofthe web of paper or other fibrous mate to 2% based on the phenolicconstituent, of an rial with resinous substances or compositions inalkaline or other suitable catalyst, stopping the 40 the form of clearaqueous dispersions which are reaction before there is any precipitationor sepad lutable with further'quantities of water. These ration ofresinoid.. The resulting relatively clear resinous compositions areapparently not true liquid dispersion will normally contain aboutaqueous solutions since there is a limit to the 60% resinoid, and willtolerate the addition of amount of water which maybe added withoutsubstantially more than an equal amount of causing resin precipitationwith attendant cloudwater without becoming cloudy 'or precipitating ingof the dispersion. In general, the most satisthe resinoid. If a drop ofthe liquid is applied to factory dispersions for use onwet paper pulphave a Wet fibrous surface, it does not remain conbeen found to be thosewhich will tolerate the adcentrated on the area to which it is applied,but

amount of water without initiating clouding or sheet. Neither does itrequire a; neutralizin precipitation of the resinoid. In other words, aacidifying agent to deposit the resinoid. resin dispersion containingabout 60% of res- A-reaction product of the phenolic typ can be lnoidwill .tcleraie an additional quantity of water made dilutable with waterunder operating con- 55 sufficient to give a clear unclouded resindisperditions differing from the above, such as using a 55 v0 dition ofsubstantially more than an equal immediately disappears into the mass ofthe smaller amount of alkaline catalyst and reacting for a longer periodof time, or until the reaction mixture separates into two layers, andthen adds ing up to 540% more of caustic based on phenol 5 to obtain anaqueous solution, or a large amount of alkaline catalyst, say about 540%sodium hydroxide based on phenol, may be used in the initial reactionwhen a liquid mass results which can be diluted with water as desired.However, as the i amount of caustic used is increased beyond 1 or 2% themass appears to take on more and more the characteristicsof a resinoidsoap in solution, and at 4% or more, to exhibit the properties of truesalt solutions to the extent of requiring l5 precipitation orneutralization by known means such as alum to remove caustic present inexcess of 4%, and preferably caustic in excess of 2% either before orafter applying the resinous composition to the fibrous sheet.

In accordance with the present invention,

therefore, it has been found that to avoid removal of caustic present inexcess of 2% without resorting to precipitation or neutralization it isnecessary to use not in excess of 2% of an alkaline catalyst duringresin condensation, and

moreover, that the condensation should be in- -terrupted before there isany precipitation or separation of the resinoid.

It has been found, furthermore, that the aque- 80 ous mass need not beof an alkaline character.

Instead the alkaline catalyst may be completely neutralized bysuiiicient acid and the neutralized solution may be used. or a smallamount of an organic .acid such as phenol, tannic acid, citric 88 acid,lactic acid, etc., can be added to give an acid reaction, and stableaqueous masses arethereby obtained which can be diluted withsubstantially more than an equal amount of water without clouding orprecipitating the resinoid.

40. ypical examples for the preparation of hydrophile resinoids suitablefor the purposes of this application are the following:

Example 1 100 parts of phenol and 80 parts of aqueous formaldehyde (40%solution) are reacted in the presence of 0.8 part sodium hydroxide forabout 30 minutes. At the end of the reaction period, the liquid mass isstill clear and no precipitation has occurred. It is dehydratedpreferably in vacuo until the resinoid content formed constitutes aboutof the total mass. The viscosity of the finished dispersion will beabout 80-100 55 cp. If the liquid mass is diluted with an equal weightof water or until the resinoid content is about 30% it still remainsclear and suitable for use with alpha cellulose fibers, pulp or groundwood. a 69 When cresols or other higher phenols are used as a componentof the resinoid, or when a more extended dilution with water isdesirable, it is generally advantageous to include a volatilewater-soluble organic solvent, such as alcohol, in 55 the liquid mass toavoid precipitation of the resinoid. For example, if alcohol is presentin an amount of about 10% of the water the composition may be diluted toa resinoid content of as little as 5% of the total mass. However, evenv70 without the inclusion of an organic solvent the mass is not renderedunusable even by dilution until clouding occurs for the hydrophileproperty ofidistributing in water or spreading and disappearing whenapplied to a wet fibrous surface is still manifested,

tannic acid, rendering the liquid mass slightly Example 2 100 parts ofcresol and 87.5 parts of aqueous formaldehyde (40% solution) and 5.3parts ammonium hydroxide (28% solution of ammonia 5 in water) arereacted 30 minutes at C. The reaction mass is then dehydrated preferablyin vacuum until a test portion of the resinv is hard and brittle whendropped into water at 2 C. 73.7 parts of denatured alcohol are added togive 10 a spirit varnish containing about 60% resinoid. Such adispersion-will have a viscosity of about 80-100 op. 50 parts of thisdispersion blended with 50 parts of the hydrophile resin described inExample 1 may be diluted with parts of 15 water to give awater-alcohol-resin dispersion which is slightly opalescent but suitablefor treating a web of paper or other fibrous material.

Example 3 145 parts of phenol, 145 parts formalin and 1 p'art sodiumcarbonate are reacted 1 hour under reflux. 0.75 part of concentratedsulfuric acid are added to the clear liquid and then 1 part of acid torosolic acid. It remained clear and could 'be diluted with an equalweight of water without clouding or precipitating the resin. Such asolution may be used in the treatment of cellulose products. 0 Example 4108 parts cresol, parts formalin, 160 parts water and 3 parts ammoniasp. g. .897 were heated to boiling under a reflux condenser for 30minutes, after which time the reaction mix- 35 ture was still a clearliquid. It was then dehydrated until about parts of a viscous resin wasobtained still containing about 18% water. This was dissolved in 43parts of alcohol containing 2 parts lime. The resulting dispersion wasclear and could be diluted with at least an equal quantity of water. Itcould be used with advantage for the treatment of cellulosic materials.

Other resins or resinoids which have, or can 45 be given, a hydrophilecharacter, such as rosin and other natural resins, such as shellac,ureaformaldehyde resinoids, resins of the alkyd type and the like mayalso be advantageously used in practicing the invention. 50

Example 5 60 parts urea and 160. parts aqueous formaldehyde 40% solutionand 1 part hexamethyiene tetramine were boiled under a reflux condenserfor 15 minutes. The reaction mixture was a clear liquid at the end ofthereaction .period. 50 parts denatured alcohol were added and 2 parts ofcitric acid which was suii'icient acid to render the liquid resinousmass, just faintly acid 0 to litmus. This liquid resinous mass could bediluted with an equal quantity of water without initiating clouding, ifused within three hours after completion of the reaction, and wassuitable for use with cellulosic compositions. On 65 standing more thanthree hours, however, the liquid resinous mass tolerated less and lesswater.

The hydrophile resinous substances are preferably applied by passing thedried or undried sheet through a. bath of the resinous composition 70 orby spraying the resinous composition upon the surface of the dried orundried fibrous; sheet.

It is particularly advantageous to apply the resinous composition to theundried. sheet as in this case one-drying operation is eliminated. 75

For example, the liquid resinous composition may be applied to the paperweb as it comes from the wire of a Fourdrinier machine or analogousdevice. In this case the sheet has typically a water content of about60% and the liquid resinoid composition immediately penetrates anddisappears into the sheet.

When a sheet or a stack of sheets treated as just described is dried andsubjected to hot pressing or calendering a most marked and unexpectedresistance to moisture absorption is brought about as well as a greatlyimproved surface appearance.

After treatment of the fibrous sheet with liquid resinoid composition,it is dried. If the composition comprises a resinoid of theheathardenable type the drying operation is preferably so carried outthat the moisture content is removed without materially advancing thestage of polymerization of the resinoid.

If a laminated product is desired the drying operation is advantageouslyconducted as follows: The web of treated fibrous material is rolled on acylinder or similar device until the desired thickness of board isobtained. The board is then cut from the cylinder and dried, preferablyby hanging in lofts. After the boards are dried they are subjected tocombined heat and pres sure between heated platens, whereby well bondedlaminated structures of high moisture resistance are produced.

This method provides an eifective and eco-- nomical way of producinglaminated structures as it obviates the necessity of coating andsuperposing a number of separate sheets.

When aqueous resinous compositions containing an organic solvent areused, the proportion of such solvent is preferably limited to such anamount, depending on the particular solvent, that after application ofthe composition to a fibrous surface and evaporation of the solvent,

sufiicient water remains to insure proper distribution of the hydrophileresinous content. Enough water should remain after removal of thesolvent to prevent undue concentration and agglomeration of the resin.When a wateralcohol mixture is used the alcohol may constitute as muchas of the mixture without disturbance of the hydrophile action whenit-is evaporated. When the residual water is thereafter removed, theresinous substance remains associated with the fiber, apparently in theform of extended films.

The application of hydrophile resinous compositions is not limited tothe procedures described above. The compositions can, for example, besprayed or dripped onto the web Just prior to its passage under themaking roll or onto the sheet as it winds upon the making roll. Anotheralternative method comprises spraying a partially dried sheet while itis passing through the paper drier, or to apply the resinous compositionthereto by means of a contact roller. It is not essential that the paperbe in a wet condition, as the resinous composition may be applied to thepaper when dry or partially dried; obvious-1y, however, it is usuallyadvantageous to make the application to the sheet while in the wetcondition to avoid a second drying.

The present invention has been found to be of particular advantage whenapplied to fibrous sheet material which has had a binding agent,

such as a phenolic resinoid, a resin or other binder, associatedtherewith in the process of manufacture. An example of such fibroussheet material which has given particularly desirable results in thepresent invention are resinoidcontaining fibrous sheets produced by theSocalled wet process. In a typical form of this process a solid phenolicresinoid in powdered or sludge form is added to the fiber pulp in abeater and thoroughly mixed. The pulp is made into a sheet in the usualmanner and dried. If, before drying such sheets, they are treated with aliquid hydrophile resinous composition, for example a phenolic resinoidcomposition, in the manner described above, laminated structures made bysuperposingthe dried sheets and subjecting the stack to heat andpressure, are found to have greatly reduced water absorption, even whenthe added resinoid is as low as 0.5% of the sheet. The water absorptionis normally reduced to onetenth or less of its original value by-thetreatment of the invention, although the added resinoid amounts to onlyone-third to one twentyfifth'of the resinoid originally present.

Not only is there the marked and unexpected decrease in water absorptionof the finished product, due to the application of a hydrophile resinoussubstance to a resin-containing sheet, but the material produced inaccordance with the invention also exhibits a substantial improvement inthe surface appearance after molding or hotpressing into laminated orboard stock. An increased uniformity of resin distribution in the bodyof the material is also obtained. As a result of this improvementhot-pressed laminated structures and other articles produced by themethod of the invention can, for example, be sanded without theformation of a striated surface effectsuch as results from the sandingof laminatiad material made by the usual method of coating andimpregnating sheets with alcoholic or other solutions of resinoids, andremoving the solvent.

This application is a continuation-in-part of our application Serial No.727,582, filed May 25, 1934. 7

We claim:

l. Fibrous composition having incorporated therewith a binder andin'addition having uniformly associated with the fibers thereof a hyddrophile heat-hardened phenolic resinoid capable of admixture with up to70 parts of water per 30 parts of the resinoid in neutral conditionwithout clouding or precipitation.

2. Fibrous composition having incorporated therewith a phenolic resinoidbinder and in addi tion having uniformly associated with the fibersthereof a hydrophile heat-hardenable phenolic resinoid capable ofadmixture with up to 70 parts of water per 30 parts of the resinoid inneutral condition without clouding or precipitation.

3. Fibrous composition having incorporated therewith from 15 to 50% of'a phenolic resinoid binder and in addition having uniformly associatedwith the fibers thereof from 0.5 to 10% of a hydrophile heat-hardenablephenolic resinoid capable of admixture with up to 70 parts of water per30 parts of the resinoid in neutral condition without clouding orprecipitation.

GORDON E. WIGHTMAN. ERNEST KRITZMACHER.

CERTIFICATE or commoner. .Patent No. 2,229,557. I January 21,- 1911.1.combo: E. WIGHTMAN, ET AL.

It is hereby c of the above numbered patent requiring correction asfollows: Page}, secline 51, claim 1, for "heat-hardened" reqd--heat-hardenab1e--;

Patent should be read with this correction therein 0nd column,

and that the said Letters that the same may conform to the record of thecasein the. Patent Offi Signedand sealed this 18th day of February, A.D. 1914.1.

Henry Van Arsdele (Seal) ertified that error appears in the printedspecification Acting Commissioner of Patents.

